In data transmission networks there is a problem when data is transmitted at high rates over a plurality of circuits of the type that comprise multi-pair data communication cable. In particular, at high transmission rates, each wiring circuit itself both transmits and receives electromagnetic radiations so that the signals flowing through one circuit or a wire pair may couple with the signals flowing through another wire pair. The unintended electromagnetic coupling of signals between different pairs of conductors of different electrical circuits is called crosstalk and is a source of interference that often adversely affects the processing of these signals. The problem of crosstalk in information networks increases as the frequency of the transmitted signals increases.
A high speed data transmission cable is typically terminated by a modular plug which conventionally comprises an insulating housing in which a planar array of closely spaced parallel passages receive the ends of respective cable wires. The cable typically comprises four circuits defined by eight wires arranged in four twisted pairs. Typically, the cable is terminated by a modular plug having eight contacts engaging the ends of the eight wires, which are received in respective wire-receiving passages arranged in a row. Specified ones of the four pairs of the plug contacts are assigned to terminate respective specified ones of the four cable wire pairs according to ANSI/EIA/TIA standard 568. For example, the standard 568B contact assignment for the wire pair designated #1 is the pair of plug contacts located at the 4-5 contact positions. The cable wires of the pair designated #3 are, according to standard 568, terminated by the plug contacts located at the 3-6 positions, which saddle the 4-5 plug contacts that terminate wire pair #1. Near-end crosstalk between wire pairs #1 and #3 during high speed data transmission has been found to be particularly troublesome in modular plugs that terminate cable according to standard 568B.
The above problem is partially solved in U.S. Pat. No. 5,628,647 which describes an electrical connector wherein the modular plug includes an insulating or dielectric housing having a plurality of wire-receiving passages disposed in first and second substantially parallel planar arrays spaced one above the other, the passages of the first planar array being staggered in position with respect to the passages of the second planar array. The end of a first wire of each of the first and second wires or signal pairs is received in a respective wire-receiving passage in the first planar array while the end of a second wire of each of the first and second signal pairs is received in a respective wire-receiving passage in the second planar array. The wire-receiving passages in which the wire ends of the first and second wire pairs are received are selected such that the pins of the first signal pair are situated in a first pair plane and the pairs are received are selected such that the pins of the first signal pair are situated in a first pair plane and the pins of the second signal pair are situated in a second pair plane that intersects the first pair plane so that the signal loops generated by the signal pairs are oriented at an angle to each other.
However, there are now new classes defining high speed data transmission. For Example, performances to be met for class E correspond to the range of signals having a frequency up to 200 MHz and even 250 MHz. Thus there remains a need to further improve the connector performances, and in particular to reduce further the Near end crosstalk (NEXT) between the different pairs of the connector, rather than just between pair #1 and pair #3 as addressed by standard 568B.